Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

substances. Substantial uncertainty also exists regarding the identity of other ingredients in
formulations further complicating our ability to predict overall toxicity to salmonids and their
prey as a result of pesticide use. Exposed populations are at increased risk of reduced abundance
and productivity from these chemicals. However, NMFS is unable to accurately describe the
level of risk.
Conclusion on population­level effects
We conclude that many of the populations of threatened and endangered salmonids covered by
this consultation will likely show reductions in viability, particularly those that are comprised of
juvenile life histories that rear for weeks to years in freshwater habitats found in intensive
agricultural and residential/urban areas. Juvenile coho salmon, steelhead, and ocean- and
stream-type Chinook salmon use these types of rearing areas for extended periods which
overlaps with pesticide applications. Of greatest concern are for those independent populations
for each ESU or DPS distributed in high use areas of carbaryl, carbofuran, and methomyl.
Based on these facts, we expect that where the geographic range of listed populations overlaps
with intensive cropping patterns and urban/residential areas severe effects to abundance and
productivity are anticipated from exposure to the three pesticides. However, due to the
impending phase out of carbofuran, we expect the likelihood of exposure and therefore toxicity
to decline rapidly as existing products stocks are depleted. Population effects are largely a result
of reduced salmonid prey abundances and subsequent reduced growth of juveniles. Although
less of a factor, individual fitness consequences are also likely in some areas due to impaired
swimming.
Effects to Designated Critical Habitat: Evaluation of Risk Hypotheses
Presently, critical habitat has been designated for 26 of the 28 listed salmonid ESUs, all of which
is located within the action area. Designated critical habitat within the action area includes
spawning and rearing areas, freshwater migratory corridors, and nearshore and estuarine areas,
and includes essential physical and biological features. When NMFS designated critical habitat
for the 26 salmonid ESU/DPSs, NMFS identified PCEs essential for the conservation of the
species. The PCEs NMFS identified are those sites and habitat components that function to
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